European leaders have thrown their weight behind a gathering international crackdown on tax evasion, backing US-led efforts to develop a new global template to combat banking secrecy.

Amid mounting public outrage in Britain, France, Germany and Ireland over individual and corporate tax scandals, an EU summit pledged to clamp down through the sharing of information on the assets and gains of nationals banking in other countries.

"There is real momentum growing on tax," David Cameron said in Brussels. He said he hoped to make his chairmanship of the G8 summit in Northern Ireland next month a turning point.

"At the international level, the EU will play a key role in supporting and promoting the automatic exchange of information as the new international standard," the summit agreed, welcoming "ongoing efforts made in the G8, G20 and OECD to develop a global standard".

The special one-day summit was the first time European leaders had grappled with the increasingly incendiary issue of tax evasion and avoidance. Germany has recently been rocked by revelations over the tax affairs of the Bayern Munich president, Uli Hoeness. In France, the cabinet minister responsible for tax collection had to resign after admitting to having a secret account in Switzerland.

The intense debate in Britain and Ireland over the tax behaviour of multinationals such as Apple, Google and Amazon have put the issue at the top of the political agenda.

Diplomats and officials conceded that the real gamechanger in the international campaign had been the Obama administration, which has been insisting on bilateral agreements with other countries, known as Fatca, on obtaining information of US nationals' assets and earnings in other countries.

"The key point is here is the developing window of opportunity to create a global information exchange. It's the US that has done it," said a senior EU diplomat. "We need some global standards on this. It's a bit of American extra-territoriality, but it's working."

Angela Merkel, the German chancellor, said the summit had achieved more on the issue than had been accomplished in years, although the meeting simply declared the direction of policy for the next few months. The leaders will return to the subject in December.

She said the summit delivered "a clear signal against tax evasion and against legal tax avoidance", making "a breakthrough possible".

EU efforts to come up with a workable information-swapping system among themselves have been stalled for a decade because Austria and Luxembourg, both renowned for their banking secrecy, refused to take part in the information flow.

This month the two countries agreed to a mandate for the European commission to negotiate with Switzerland and other non-EU European over the issue.

Until now Luxembourg and Austria have blocked the EU information-sharing scheme because Switzerland is not involved, while the Swiss have refused to negotiate over their participation until the scheme is operable all across the EU.

This stalemate was not broken on Wednesday, although the leaders said they wanted the scheme decided by December.

Jean-Claude Juncker, Luxembourg's prime minister, made clear he would not join the scheme until the outcome of the negotiations with the Swiss was clear.

Cameron, however, oozed confidence that a decade of EU stalemate had been overcome. "It's pretty clear there is going to be a full exchange of tax information between all EU countries," he said. "Potentially that's the real breakthrough."

Meanwhile his Irish counterpart, Enda Kenny, fended off accusations from the US Senate that Ireland was effectively operating as a tax haven, enabling US corporations to avoid paying tens of millions in US tax liabilities.

"Our country has had a stable corporate tax rate for many years," Kenny said. "We do not do special deals with any individual company in regard to that tax rate."

US allegations that big multinationals have been exploiting loopholes in the system in Ireland to minimise their tax liabilities have stirred strong language.

"We cannot accept that a certain number of companies can put themselves in situations where they escape paying taxes in ways that are legal," said the French president, François Hollande. "We must co-ordinate at a European level, harmonise our rules and come up with strategies to stop this."

In Brussels the unofficial calculation is that around €1tn a year in tax collection across the 27 member states is lost through highly complex legal tax avoidance schemes used by big companies, as well as through tax evasion.